A reactor furnished with fixing or attachment means of the kind mentioned above is known from British Pat. No. 1,247,148. In the known reactor the members which transmit the tensile force are fixed directly to the foot ring of the reactor vessel, which means that the vertical members transmitting the tensile force run through the radiation protection device with a relatively small radial distance from the radially inner limiting surface of said radiation protection device. The prestressing force exerted on the concrete by said members are thus unevenly distributed over the cross section of the radiation protection device and less efficient from the point of view of strength than an evenly distributed prestressing force.
Furthermore, the known construction involves the disadvantage that the prestressed tensile-force transmitting members are easily subjected to shearing forces caused by the thermal expansion of the foot ring.